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North Pamirs-Karakul lake batholith
The herein presented E-W trending Karakul lake batholith is characterised by
undeformed granodiorites to monzogranites, which intrude Carboniferous to Permian,
possibly Triassic metaclastic and metavolcanic rocks, locally accompanied by gabbroic
intrusives. U/Pb zircon ages of the batholith are interpreted as minimum crystallisation
ages at about 215.0±1.5 Ma. This age is supported by 40 Ar/ 39 Ar biotite and muscovite
ages in the range of 207 to 191 Ma, interpreted as cooling ages close to the
crystallisation age. The rocks are characterised as high-K, calc-alkaline, transitional I-
to S-type intrusive rocks with Sr (i)=0.707623 (P22) and 0.706974 (P26). �Nd (t) values are
around –4 and the depleted mantle model ages are ~1.3 Ga. The batholith is
interpreted as post-tectonic intrusion through relatively thin crust with less crustal
contribution to the magma source than determined from other Pamiran magmatic rocks
(see chapter 3.5).
Intrusions of similar age are reported in the western Kunlun: Yuan et al. (1999) dated
the Akarz mountain pluton, which is located southwest of Kudi and which intrudes a
Proterozoic basement group in the north and a lower Permian magmatic arc (Sailiyak
magmatic arc) in the south. The Akarz mountain pluton covers an area of more than
2800 km 2 , and is truncated to the south by the Mazar-Kangxiwar fault (southern margin
of the South Kunlun). Like in the Karakul lake area, the magmatic rocks are mainly
granodiorites and monzogranites, with some quartz-diorites. The U/Pb zircon age is
214.9±1.5 Ma (Yuan et al. 1999), identical to the data from the Karakul lake batholith.
The �Nd (t) values show a wide variety between –3.2 to –11.9 (5 samples), indicating
that the magma source is heterogeneous with involved continental crust. The depleted
mantle model ages are between 1.29 to 2.08 Ga (Yuan et al. 1999). A gneissic granite,
located 22 km north-east of Mazar yielded a biotite Ar/Ar isochron age of 211.8±10.8
Ma age (Xu et al. 1996, Pan 1996) supporting, like the Ar/Ar ages of the Karakul
batholith, the crystallisation age. A red porphyry volcanic rock situated close to the
granite yielded a Rb/Sr whole rock age of 180±10 Ma (Matte et al. 1996).
The Kara Kunlun or Mazar terrane consists of different subduction complexes (Fig.
3.14), which are subdivided into three units: (1) the northern Bazar Dara subduction
complex with imbricated blocks of sandstone, calc-arenite, limestone, and
metavolcanic blocks in a matrix of weakly metamorphosed Triassic deep-sea turbidites
(Xiao et al. 2002). This zone has Ordovician to Permian fossils and is situated south of
the Sailiyak magmatic arc. (2) The southern Heweitan mélange is composed of a slatephyllite
matrix with blocks of limestone, turbidite, and radiolarite with Permian to
Triassic fossils (Gaetani et al. 1990, Pan 1996, Xiao et al. 2002). The Konggashankou-
Qogir fault is the southern limit of the Heweitan subduction complex; the fault
separates Gondwana cool-water fauna in the south from Cathaysian warm-water fauna
in the north (Li et al. 1995). Thus, a suture is supposed along the Konggashankou-Qogir
fault, which can be correlated with the Jinsha suture to the east (Li et al. 1995). Xiao et
al. (2002) interpret the Heweitan rocks as a subduction complex near the trench of a
north-dipping subduction zone. (3) The Qitai forearc basins of Late Triassic turbidites
and intercalated carbonates overlie the Bazar Dara and Heweitan subduction
complexes. The sediments of the Qitai forearc basin were derived from both the
adjacent Sailiyak arc and the subduction complex. Xiao et al. (2002) conclude that the
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